Henry Eyring. The Activated Complex in Chemi.pdf


Preview of PDF document henry-eyring-the-activated-complex-in-chemi.pdf

Page 1 2 3 4 5 6 7 8 9 10 11 12 13

Text preview


The Activated Complex in Chemical Reactions
interpreted as the steric factor. It is interesting to note that if the two bending frequencies
arising from translational terms are stiff enough so that the system lies almost entirely in the
corresponding lowest states, the reaction diameter as just defined will be less than the kinetic
diameter by the factor 8π 2 IkT /h2 which may reach a value of the order of 100 for heavy
atoms and moderately high temperatures.
The present formulation of the calculation of absolute rates of chemical reactions has certain
features in common with a number of more intuitive previous treatments,13 but has more in
common with the treatment of Pelzer and Wigner. It goes beyond these in formulating the
general problem in a way susceptible to treatment with our present potential energy surfaces
and in pointing out the consequences of quantization on the temperature coefficient and the
difference in rate for isotopes. The fact that the activated complex is much like any other
molecule except in the degree of freedom in which it is flying to pieces makes possible our
comparatively simple formulation. A number of investigations are now in progress in which
the absolute rate of reaction is being calculated.
I want particularly to thank Dr. Bryan Topley for valuable discussions as it was with him the
present calculations of absolute rates were begun. I also want to thank Professors Taylor and
Webb for helpful discussions.

13

W. H. Rodebush, J. chem. Phys. 1, 440 (1933); V. K. La Mer, ibid., 1, 289 (1933); O. K. Rice and H. Gershinowitz,
ibid., 2, 853 (1934)

13